Mine are way worse than that. That just looks like crud. Mine are buckets of rust. Angle grinder and wire brush attachment would clean those up. You can never tell what the pistons will be like till you pop them out. They could salvage, but by the time you have cleaned them, split them, bought new pistons etc and put them all back together, you could have bought a set of aftermarket ones and been on your way.
It's always hard to advise on these things when you don't know what the other person has access to. I'd whizz them over, split them, strip them, pop the pistons in the lathe and just clean up the ends and give them a polish, wash them in brake cleaner and blow them out with an airline, put the new seals in and pistons, gaiters and then reassemble. But I have access to the kit and spares on the shelf. So for me, it's easy, I'd rebuild them. The key thing with so many questions on the forum is that my own time is free. So building them up would be the cost of the kit. But if you sent yours to me and I were to charge you, you'd just go and buy new ones.